Brachyrhamdia marthae

This species grows up to 7–8 cm in length. A distinctive feature of the fish is its elongated body, large fins, and forked tail. Thin, long barbels can be seen near its mouth. The coloration of adult specimens is subdued, predominantly gray and dark tones. Young catfishes appear lighter, their integuments are translucent, which can make them seem pinkish.

The species inhabits South America, primarily in the basins of the Juruá, Mamoré, and Madeira rivers. It is a freshwater demersal fish, preferring the bottom layers of the water. In its natural habitat, water parameters are characterized by a tropical temperature regime of 24 to 26 degrees Celsius and a slightly acidic environment with a pH level in the range of 6.0–7.0.

This species is generally considered peaceful. However, if the aquarium volume is insufficient, the fish may exhibit territorial behavior, competing with conspecifics for bottom areas. Similar rivalry is possible with other bottom-dwelling species. When choosing tank mates, it is recommended to prefer non-aggressive fish of comparable size that inhabit the middle and upper water layers. It is important to remember that fry and small fish that can fit into the mouth of Brachyrhamdia marthae may be eaten.

For a group of 3–4 catfishes, an aquarium of 120–130 liters will be optimal. In the aquarium's setup, key attention is paid to the bottom design. It is desirable to alternate open substrate areas with zones providing shelters. Both natural elements, such as snags, and artificial decorations are suitable as shelters. The use of gravelly, stony substrates is preferred. Lighting should be kept subdued, which can be achieved, among other things, by using floating plants for natural shading. Other decor elements are chosen at the discretion of the aquarist or according to the needs of other inhabitants. Brachyrhamdia marthae does not have high demands for keeping conditions and adapts well to various environments. Comfortable conditions for it include a temperature of 24–26°C and the following water parameters: pH 6.0–7.0, hardness up to 15 dH.

The catfish readily accepts most foods intended for aquarium fish. However, since its satiety instinct is poorly developed, there is a risk of overfeeding.

There is no information on aquarium breeding. Like other members of the genus, the species keeps to shoals of Corydoras in the wild, whose colouration it copies, and it is collected along with them. No external sexual differences have been described, and no deliberate effort is made to breed these catfish.

No diseases that affect only this species have been described. Under suitable conditions — clean water, a balanced diet and calm tank mates — health problems usually do not arise. The most common cause of illness is a decline in conditions: it weakens the immune system, and the fish becomes vulnerable to infections that are always present in an aquarium. At the first signs of trouble — lethargy, wasting, refusal of food or clamped fins — check the basic water parameters and the levels of ammonia, nitrite and nitrate first. Restoring acceptable conditions often lets the fish recover on its own. Catfish of this group have naked, scaleless skin and are therefore more sensitive to medication than most aquarium fish. Products based on malachite green and copper should be used with care and at about half the dose stated on the packaging.

When selecting individuals in a store, attention should be paid to the following signs: — fish activity and the absence of visible skin damage, such as ulcers, plaque, or hemorrhages — clean fins, which should not show signs of erosion or white spots — normal behavior, where the fish does not show signs of emaciation and actively responds to external stimuli — absence of stress signs, expressed in unnatural coloration or prolonged hovering near the water surface.